Charging device and control method

Abstract

A charging device according to an embodiment of the present invention wirelessly charges a terminal device having a power reception coil, which is disposed on a placement surface and receives power that has been wirelessly transmitted, the charging device comprising a power transmission coil that transmits power to the terminal device, and a controller. When a foreign object existing between the power transmission coil and the power reception coil is not detected before the start of wireless charging, the controller adds, in accordance with a first distance indicating the distance between the power transmission coil and the power reception coil in a height direction, a first correction term of power loss due to the foreign object after power is transmitted to the power reception coil by the power transmission coil to a calculation formula used for the foreign object detection during the wireless charging, and implements detection processing for detecting the foreign object existing between the power transmission coil and the power reception coil on the basis of the calculation formula after the start of the wireless charging.

Description

Charging device and control method

[0001] This disclosure relates to a charging device and a control method.

[0002] Conventionally, charging devices are known that move a power transmitting coil to the position of the power receiving coil of a terminal device with a built-in battery, and perform wireless charging of the terminal device using the power transmitting coil. Foreign object detection in wireless charging is standardized in the Qi standard, an international standard for contactless charging, using a method called MPLA (MPP (Magnetic Power Profile) Power Loss Accounting). MPLA detects whether there is a foreign object such as metal between the charging device and the terminal device based on power loss during wireless charging.

[0003] Japanese Patent Publication No. 2013-128400

[0004] However, the calculation of power loss based on MPLA does not take into account the increase in power loss due to the increased distance between the transmitting and receiving coils. Therefore, when the distance increases, it is impossible to distinguish whether the problem is due to the intrusion of foreign objects such as metal between the charging device and the terminal device, or a misalignment between the charging device and the terminal device. Furthermore, in the case of misalignment, there is no heat generation from the foreign object, so there is no need to reduce the power or stop charging, and there is room for improvement.

[0005] One of the problems that this disclosure aims to solve is to provide a charging device and control method that can improve the accuracy of foreign object detection between the charging device and the terminal device, corresponding to the positional relationship between the transmitting coil and the receiving coil in wireless charging.

[0006] The charging device according to this disclosure is a charging device that wirelessly charges a terminal device having a receiving coil that is placed on a mounting surface and receives power transmitted wirelessly, and comprises a transmitting coil that transmits power to the terminal device and a controller. Before wireless charging starts, if the controller does not detect any foreign matter between the transmitting coil and the receiving coil, it adds a first correction term for power loss due to foreign matter after power transmission from the transmitting coil to the receiving coil to a calculation formula used for detecting foreign matter during wireless charging, according to a first distance indicating the height distance between the transmitting coil and the receiving coil, and after wireless charging starts, it performs a detection process to detect any foreign matter between the transmitting coil and the receiving coil based on the calculation formula.

[0007] According to this disclosure, the accuracy of foreign object detection between the charging device and the terminal device can be improved in accordance with the positional relationship between the transmitting coil and the receiving coil in wireless charging.

[0008] Figure 1 is a diagram showing an example of the schematic configuration of a charging system according to an embodiment. Figure 2 is a diagram showing an example of the configuration of a charging system according to an embodiment. Figure 3 is a schematic diagram for explaining the height distance between the power transmitting coil and the power receiving coil according to an embodiment. Figure 4 is a flowchart showing an example of the processing flow performed by the charging device according to an embodiment. Figure 5 is a flowchart showing an example of the processing flow performed by the charging device according to an embodiment. Figure 6 is a flowchart showing an example of the processing flow performed by the charging device according to an embodiment. Figure 7 is a schematic diagram for explaining the height distance between the power transmitting coil and the power receiving coil according to a first modified example. Figure 8 is a flowchart showing an example of the processing flow performed by the charging device according to the first modified example. Figure 9 is a flowchart showing an example of the processing flow performed by the charging device according to the first modified example. Figure 10 is a flowchart showing an example of the processing flow performed by the charging device according to the first modified example. Figure 11 is a diagram showing an example of the hardware configuration of a charging system according to an embodiment and a modified example.

[0009] Hereinafter, embodiments of the charging device according to this disclosure will be described with reference to the drawings. In this description, components having the same or substantially the same function as those described above in previously shown drawings will be denoted by the same reference numerals, and descriptions may be omitted as appropriate. Furthermore, even when representing the same or substantially the same parts, the dimensions and proportions may be shown differently in the drawings. In addition, for example, from the viewpoint of ensuring the readability of the drawings, reference numerals may be denoted only for the main components in the description of each drawing, and reference numerals may not be denoted for components having the same or substantially the same function as those described above in previously shown drawings.

[0010] In addition, in the descriptions of this disclosure, components having the same or substantially the same function may be distinguished by adding alphanumeric characters to the end of the reference numeral. Alternatively, if multiple components having the same or substantially the same function are not to be distinguished, they may be described together by omitting the alphanumeric characters at the end of the reference numeral.

[0011] (Embodiment) Figure 1 is a diagram showing an example of a schematic configuration of a charging system 100 according to an embodiment. As shown in Figure 1, the charging system 100 comprises a charging device 10 and a terminal device 20.

[0012] The charging device 10 is a device capable of wireless charging. The housing of the charging device 10 is provided with a mounting surface 11. The mounting surface 11 is a surface on which the terminal device 20 to be wirelessly charged is placed. In this embodiment, one example described is a configuration in which the mounting surface 11 is a part of the outer surface of the housing and is a two-dimensional planar area.

[0013] In this embodiment, we will explain assuming that the mounting surface 11 is a two-dimensional plane along a plane defined by a first direction and a second direction perpendicular to the first direction. Furthermore, as shown in Figure 1, we will explain assuming that the first direction is the X-axis direction and the second direction is the Y-axis direction. The X-axis direction and the Y-axis direction are mutually orthogonal directions along the two-dimensional plane of the mounting surface 11. The Z-axis direction, which is perpendicular to the X-axis direction and the Y-axis direction, will be explained as coinciding with the thickness direction of the housing. The Z-axis direction coincides with the direction in which the terminal device 20 and the charging device 10, which are mounted on the mounting surface 11, face each other.

[0014] In this embodiment, the positive direction of the Z-axis may also be expressed as "upward," "upper side," or "upper surface side." Similarly, the negative direction of the Z-axis may also be expressed as "downward," "lower side," or "lower surface side." Furthermore, the direction of the Z-axis may also be expressed as the "height direction." The plane and the direction within the plane stretched by the X-axis and Y-axis may also be expressed as the "horizontal plane" and the "horizontal direction," respectively.

[0015] In this embodiment, "parallel," "horizontal," "vertical," and "orthogonal" refer not only to perfectly parallel, horizontal, vertical, and orthogonal lines, but also to cases where they deviate from them within a margin of error. Furthermore, "approximately" means being identical within a general range.

[0016] The charging device 10 comprises at least a power transmission coil 12, a moving mechanism 15, a plurality of detection coils 16, and a controller 17. For example, the power transmission coil 12, the moving mechanism 15, the plurality of detection coils 16, and the controller 17 are housed within the casing of the charging device 10.

[0017] The power transmission coil 12 is a coil for transmitting power to the terminal device 20. More specifically, the power transmission coil 12 is a charging coil that generates an alternating magnetic field for charging and supplies power to the power receiving coil 22 of the terminal device 20 through electromagnetic induction with the power receiving coil 22.

[0018] A magnetic sheet 13 is provided on the back of the power transmission coil 12. The magnetic sheet 13 suppresses the influence of the alternating magnetic field generated by the power transmission coil 12 on various electronic circuits located in the charging device 10 on the side opposite to the detection coil 16 relative to the power transmission coil 12. Furthermore, the magnetic sheet 13 ensures that the power generated by the alternating magnetic field in the power transmission coil 12 is effectively supplied to the power receiving coil 22. In other words, the magnetic sheet 13 contributes to preventing malfunctions of various electronic circuits in the charging device 10 and to improving the power transmission efficiency from the power transmission coil 12 to the power receiving coil 22. In this embodiment, the power transmission coil 12 is placed on a transport table 14 via the magnetic sheet 13.

[0019] The moving mechanism 15 is a mechanism that changes the relative position between the power transmitting coil 12 and the power receiving coil 22. The moving mechanism 15 is a mechanism that moves the power transmitting coil 12 along the mounting surface 11. In this embodiment, the moving mechanism 15 moves the transport table 14, on which the magnetic sheet 13 and the power transmitting coil 12 are placed in that order, along the mounting surface 11, thereby moving the power transmitting coil 12 placed on the transport table 14 together with the magnetic sheet 13 along the mounting surface 11.

[0020] The moving mechanism 15 is configured using at least one drive motor, such as a stepping motor or servo motor, and support members. The moving mechanism 15 is configured to move the transport platform 14 along the mounting surface 11 in both the X-axis direction and the Y-axis direction by the drive of the drive motor. In other words, the power transmission coil 12 is configured to move along a two-dimensional plane, which is the XY plane along the mounting surface 11, by the moving mechanism 15.

[0021] The multiple detection coils 16 are a group of coils for detecting the position of the power receiving coil 22 of the terminal device 20 on the mounting surface 11. The position of the power receiving coil 22 of the terminal device 20 is represented by its position in a two-dimensional plane consisting of an XY plane along the mounting surface 11. If the power receiving coil 22 is an annular induction coil as shown in Figure 1, the position of the power receiving coil 22 is defined, for example, as the position of the center point of the annulus in the XY plane along the mounting surface 11. The multiple detection coils 16 are arranged below the mounting surface 11 within the housing of the charging device 10, along the mounting surface 11. For example, the multiple detection coils 16 are arranged in a matrix in directions that intersect each other.

[0022] The charging device 10 only needs to be configured to detect the position of the power receiving coil 22 of the terminal device 20 placed on the mounting surface 11. For example, the charging device 10 may be equipped with various sensors such as a weight sensor, pressure sensor, or light sensor that can detect the position of the terminal device 20 placed on the mounting surface 11, or a camera that takes pictures of the mounting surface 11.

[0023] The charging device 10 is a device that performs contactless charging, or wireless charging, on a terminal device 20 to be charged, which is placed on the mounting surface 11 of the charging device 10. Here, wireless charging means charging by wireless means. In this disclosure, a form in which wireless charging means charging by electromagnetic induction will be described as an example.

[0024] The Qi standard, established by the Wireless Power Consortium (WPC), is an international standard for wireless charging. The Qi standard specifies two types of charging: high-power charging (hereinafter referred to as high-power charging) and low-power charging (hereinafter referred to as low-power charging). In this embodiment, high power is an example of the first power, and low power is an example of the second power.

[0025] For example, high-power charging is performed at a maximum of 15 W, and low-power charging is performed at a maximum of 5 W. High-power charging is called EPP (Extended Power Profile), and low-power charging is called BPP (Baseline Power Profile). Furthermore, high-power charging standards such as MPP (Magnetic Power Profile), which will be described later, have also been proposed. Regardless of the standard name, relatively high-power charging and low-power charging are defined.

[0026] In such wireless charging, as an example, in a state where the terminal device 20 to be charged is placed on the upper surface (e.g., the placement surface 11) of the placement portion of the charging device 10, the power transmission coil 12 of the charging device 10 is moved by the moving mechanism 15 to approach the power reception coil 22 of the terminal device 20, thereby positioning the power transmission coil 12 and the power reception coil 22.

[0027] In wireless charging, charging is more efficient as the positional relationship between the power transmission coil 12 of the charging device 10 and the power reception coil 22 of the terminal device 20 to be charged is closer to an opposing arrangement. Within the Qi standard, MPP for high-speed charging using a magnet is in the process of being standardized. For this reason, the charging device 10 according to the present disclosure may include a magnet arranged together with the power transmission coil 12.

[0028] The terminal device 20 is a terminal used by a user. The terminal device 20 is an example of an electronic device incorporating a battery 24. The terminal device 20 is configured to be operable using power from the built-in battery 24. The battery 24 is configured to be chargeable with power wirelessly transmitted from the charging device 10. For the terminal device 20, various electronic devices such as smartphones, tablet terminals, audio players, and mobile phones can be appropriately used, for example.

[0029] The terminal device 20 further includes at least a power receiving coil 22. The power receiving coil 22 is configured to be able to receive power wirelessly transmitted from the charging device 10. The power receiving coil 22 is, for example, an induction coil electromagnetically coupled to the power transmission coil 12 of the charging device 10. The power induced by the power receiving coil 22 is supplied to the battery 24. A magnetic sheet 26 is provided on the back surface of the power receiving coil 22. The magnetic sheet 26 suppresses the occurrence of malfunction of various electronic circuits provided in the terminal device 20.

[0030] Figure 2 is a diagram showing an example of the configuration of a charging system 100 according to the embodiment. In addition to the power receiving coil 22, the terminal device 20 includes a capacitor 21, a power receiving circuit 25, and a load 28. The power receiving coil 22 is connected between the capacitor 21 and the power receiving circuit 25. One end of the power receiving coil 22 is connected to the capacitor 21, and the other end is connected to an input node of the power receiving circuit 25.

[0031] The capacitor 21 is connected between the power receiving coil 22 and the power receiving circuit 25. One end of the capacitor 21 is connected to the power receiving coil 22, and the other end is connected to an N-side input node of the power receiving circuit 25. The capacitor 21 receives a power supply voltage from the power receiving coil 22 and transmits it to the power receiving circuit 25. The power receiving circuit 25 generates a charging current corresponding to the induced electromotive force generated in the power receiving coil 22. The load 28 is, for example, a battery, and is charged by the output current of the power receiving circuit 25.

[0032] In addition to a power transmission coil 12, a moving mechanism 15, a plurality of detection coils 16, and a controller 17, the charging device 10 includes a DC power supply 101, a DC-DC converter circuit 102, an inverter circuit 103, a capacitor 104, a voltage detection circuit 105, a current detection circuit 106, a terminal signal demodulation circuit 108, a position detection pattern coil 109, and a position detection circuit 110.

[0033] The DC power supply 101 generates a DC power supply voltage. The DC power supply 101 may be, for example, a battery, a power supply circuit that receives a DC power supply voltage from the outside, or a power supply circuit that receives an AC power supply voltage from the outside and converts it into a DC power supply voltage. The DC power supply 101 supplies the DC power supply voltage to the DC-DC converter circuit 102.

[0034] The DC-DC converter circuit 102 converts the DC power supply voltage to a DC voltage under the control of the controller 17. The DC-DC converter circuit 102 may boost the DC power supply voltage to convert it to a DC voltage, step down the DC power supply voltage to convert it to a DC voltage, or convert the DC power supply voltage to a DC voltage while adjusting the waveform while maintaining an equal voltage. The DC-DC converter circuit 102 supplies the converted DC voltage to the inverter circuit 103.

[0035] The inverter circuit 103, under the control of the controller 17, converts the supplied DC voltage into a single-phase AC voltage. The inverter circuit 103 can supply the single-phase AC voltage to the power transmission coil 12 via the capacitor 104. As a result, the inverter circuit 103 can drive the power transmission coil 12 via the capacitor 104.

[0036] The capacitor 104 is connected between the inverter circuit 103 and the power transmission coil 12. One end of the capacitor 104 is connected to the P-side output node of the inverter circuit 103, and the other end is connected to the power transmission coil 12. The capacitor 104 receives a single-phase AC voltage from the inverter circuit 103 and transmits it to the power transmission coil 12. By providing the capacitor 104 between the inverter circuit 103 and the power transmission coil 12, the AC voltage can be smoothed, improving the efficiency and stability of wireless charging.

[0037] The power transmission coil 12 is connected between the inverter circuit 103 and the capacitor 104. One end of the power transmission coil 12 is connected to the N-side output node of the inverter circuit 103, and the other end is connected to the capacitor 104.

[0038] The voltage detection circuit 105 detects the voltage on the input side of the inverter circuit 103. The voltage detection circuit 105 has a detection node connected to the line connecting the DC-DC converter circuit 102 and the inverter circuit 103. The voltage detection circuit 105 may also detect the voltage on the input side of the inverter circuit 103 via the detection node. The voltage detection circuit 105 supplies the detected voltage to the controller 17.

[0039] The current detection circuit 106 detects the output current of the inverter circuit 103. The detection node of the current detection circuit 106 is connected to the line connecting the inverter circuit 103 and the capacitor 104. The current detection circuit 106 supplies the detected current to the controller 17. For example, the current detection circuit 106 detects the peak frequency of the Q value of the power transmission coil 12 and supplies (transmits) it to the controller 17.

[0040] The moving mechanism 15 is capable of moving the power transmission coil 12 in the XY direction under the control of the power transmission coil control unit 172 of the controller 17, which will be described later. The moving mechanism 15 moves the power transmission coil 12 in the XY direction in accordance with the control of the power transmission coil control unit 172 so as to approach the position of the power receiving coil 22. This allows the position of the power transmission coil 12 to be aligned to coincide with the position of the power receiving coil 22. In this embodiment, the XY direction is also referred to as the horizontal direction.

[0041] The terminal signal demodulation circuit 108 extracts the modulation component from the AC signal and reconstructs the information when an AC signal is received from the terminal device 20. The terminal signal demodulation circuit 108 may reconstruct the information using a frequency modulation method, an amplitude modulation method, or another modulation method. The terminal signal demodulation circuit 108 supplies the reconstructed information to the controller 17. The information here is information exchanged between the charging device 10 and the terminal device 20, and includes information measured or calculated by the charging device 10, or individual information of the terminal device 20, and is also called configuration information.

[0042] The position detection pattern coil 109 is positioned between the power transmission coil 12 and the mounting surface 11 (see Figures 1 and 2). The position detection pattern coil 109 includes a plurality of coils distributed in the XY direction.

[0043] The position detection circuit 110 is connected between the position detection pattern coil 109 and the controller 17. The position detection circuit 110 is connected to each of the multiple coils of the position detection pattern coil 109. The position detection circuit 110 detects the position of the power receiving coil 22. The position detection circuit 110 can detect the position of the power receiving coil 22 under the control of the controller 17.

[0044] The controller 17 may detect the position of the power receiving coil 22 in the terminal device 20 using the position detection pattern coil 109 and the position detection circuit 110. The position detection circuit 110 supplies pulses to each of the multiple coils of the position detection pattern coil 109 in response to the control of the controller 17. Each of the multiple coils generates a magnetic flux corresponding to the pulse. When the multiple coils receive a magnetic flux as an echo from the power receiving coil 22, they generate an induced current corresponding to it and return it to the position detection circuit 110. The position detection circuit 110 identifies the position of the power receiving coil 22 according to the induced current of each of the multiple coils. The position detection circuit 110 supplies the identified XY position to the controller 17.

[0045] The controller 17 is configured to comprehensively control each part of the charging device 10, for example, to execute a charging process. The controller 17 includes a terminal position detection control unit 171, a power transmission coil control unit 172, a foreign object detection unit 173, and a charging state control unit 174. Each part of the controller 17 may be implemented in software as a module configured within the controller 17 by the execution of software.

[0046] For example, the controller 17 may be a system comprising a processor, non-volatile memory, and volatile memory. The non-volatile memory stores the program. The processor may start up by reading the program from the non-volatile memory triggered by the power-up of the charging device 10, and may deploy modules corresponding to each part onto the volatile memory all at once during compilation or sequentially as processing progresses. In this way, the processor may operate according to the program. Alternatively, each part of the controller 17 may be implemented in hardware as a circuit configured within the controller 17. Alternatively, some of the parts of the controller 17 may be implemented in software and the rest in hardware.

[0047] When the terminal device 20 is placed on the mounting surface 11, the terminal position detection control unit 171 detects the position of the terminal device 20. Specifically, when the terminal device 20 is placed on the mounting surface 11, the terminal position detection control unit 171 sends an Analog Ping to the terminal device 20, sends a predetermined Protection request, and then sends an Object Detection request.

[0048] Furthermore, the terminal location detection control unit 171 determines whether the terminal device 20 has been detected. For example, if the terminal device 20 does not respond to the object detection request, the terminal location detection control unit 171 determines that the terminal device 20 has not been detected. Also, for example, if the terminal location detection control unit 171 receives a response from the terminal device 20 to the object detection request, it determines that the terminal device 20 has been detected.

[0049] Furthermore, when the terminal location detection control unit 171 detects the terminal device 20, it indicates that the presence of the terminal device 20 has been detected and sends a digital ping including a wake-up request (Wake Up Power Receiver) to the terminal device 20. In order to indicate its presence, the terminal device 20 sends signal strength data (SIG) or end power data (EPT) to the charging device 10 as a response to the digital ping. The terminal location detection control unit 171 may also send and receive various data via the power transmission coil 12.

[0050] The power transmission coil control unit 172 controls the movement of the moving mechanism 15 to set the position of the power transmission coil 12 to a position opposite the power transmission coil 22 based on the position of the power receiving coil 22 detected by the position detection circuit 110. Specifically, the power transmission coil control unit 172 controls the movement of the power transmission coil 12 in the XY direction using the moving mechanism 15, according to the position of the power receiving coil 22 detected by the position detection circuit 110.

[0051] At this time, the second distance, which indicates the distance between the transmitting coil 12 and the receiving coil 22 in the X and Y directions, is approximately equal. In other words, the transmitting coil control unit 172 controls the transmission coil 12 to move to a position where there is no positional misalignment between the transmitting coil 12 and the receiving coil 22. Then, the transmitting coil 12 is moved by the moving mechanism 15 to the position set by the transmitting coil control unit 172, and various authentications are performed between the charging device 10 and the terminal device 20.

[0052] The foreign object detection unit 173 performs a detection process to detect foreign objects present between the power transmission coil 12 and the power receiving coil 22. Furthermore, before starting wireless charging, the foreign object detection unit 173 determines whether there are any foreign objects between the power transmission coil 12 and the power receiving coil 22. Specifically, the foreign object detection unit 173 detects the peak frequency of the Q value of the power transmission coil 12, supplied by the current detection circuit 106. The foreign object detection unit 173 also determines whether there are any foreign objects between the power transmission coil 12 and the power receiving coil 22 based on the detected change in peak frequency.

[0053] For example, the foreign object detection unit 173 determines that there is a foreign object between the power transmission coil 12 and the power receiving coil 22 if there is a predetermined change in the detected peak frequency. Also, for example, the foreign object detection unit 173 determines that there is no foreign object between the power transmission coil 12 and the power receiving coil 22 if there is no predetermined change in the detected peak frequency. The predetermined change refers to, for example, a change in the peak frequency when there is no foreign object to the peak frequency when there is a foreign object.

[0054] Here, "foreign matter" refers to conductive objects such as metal fragments. For example, when wireless charging is performed, a foreign matter is an object that can cause an electric current to flow through it, leading to overheating. In other words, a foreign matter is an object that poses a risk of fire during wireless charging. Furthermore, when wireless charging is performed, a foreign matter is an object that can cause power loss due to the flow of electric current through it.

[0055] When the terminal device 20 is placed on the mounting surface 11, the charging state control unit 174 executes the detection (ping) phase process. The detection phase process is executed by the charging state control unit 174 when the foreign object detection unit 173 detects that there is no foreign object between the power transmission coil 12 and the power receiving coil 22, or when the foreign object detection unit 173 detects that there is a foreign object between the power transmission coil 12 and the power receiving coil 22.

[0056] Specifically, the detection phase processing involves the charge state control unit 174 sending an analog ping, a predetermined protection request, and then an object detection request. The charge state control unit 174 also waits until it receives a response corresponding to the aforementioned analog ping, predetermined protection request, and object detection request in order to detect whether or not an object is present within the communication range (Examine Operating Volume).

[0057] Furthermore, when the charging state control unit 174 receives a response corresponding to the transmission result, it detects the presence of the terminal device 20 and sends a digital ping including a wake-up request to the terminal device 20. In response, the terminal device 20 sends signal strength data or end power data to the charging device 10 as a response to the wake-up request in order to indicate its presence.

[0058] Then, when the charging state control unit 174 receives signal strength data or end power data from the terminal device 20, it completes the detection phase processing. The charging state control unit 174 may also use the position detection pattern coil 109 and the position detection circuit 110 to process analog ping, predetermined protection requests, and object detection requests.

[0059] Furthermore, once the detection phase processing is complete, the charging state control unit 174 executes the first configuration phase processing. The first configuration phase processing is executed by the charging state control unit 174 when the foreign object detection unit 173 detects that there is no foreign object between the power transmission coil 12 and the power receiving coil 22.

[0060] Specifically, the first setting phase involves the charge state control unit 174 sending a configuration information request to the terminal device 20 and receiving configuration information from the terminal device 20 as a response to the configuration information request. The charge state control unit 174 also calculates the coupling coefficient k using the voltage included in the configuration information. Furthermore, the charge state control unit 174 calculates the height distance between the transmitting coil 12 and the receiving coil 22 based on the calculated coupling coefficient k. Here, in the first setting phase, the height distance between the transmitting coil 12 and the receiving coil 22 is also referred to as the first distance. Next, the height distance between the transmitting coil 12 and the receiving coil 22 calculated by the charge state control unit 174 will be explained using Figure 3.

[0061] Figure 3 is a schematic diagram illustrating the height distance between the transmitting coil 12 and the receiving coil 22 according to the embodiment. Figure 3 also shows a graph and a table illustrating the relationship between the coupling coefficient and the distance. The graph in Figure 3 is a two-axis graph with the coupling coefficient on the horizontal axis (X axis) and the distance [mm] on the vertical axis (Y axis). Table T1 in Figure 3 is a table that correlates the coupling coefficient with the distance [mm].

[0062] Table T1 is a table showing the relationship between the coupling coefficient and distance, for example, before the charging device 10 starts wireless charging the terminal device 20, or after the charging device 10 has performed a simulation in advance. Graph G1 is a graph that plots the values ​​of the coupling coefficient and distance shown in Table T1, and connects adjacent plotted points with lines.

[0063] Graph G2 is the approximation curve corresponding to Graph G2. Graph G2 is, for example, a fourth-order approximation curve, and if the coupling coefficient is X and the distance is Y, then Y = 416.02X ４ -937.03X ３ +745.48X ２ The result is -264.55X + 44.618. Note that the approximation curve of graph G2 is not limited to this and changes according to the value in table T1. The charging state control unit 174 calculates the height distance between the transmitting coil 12 and the receiving coil 22 by substituting the calculated coupling coefficient k into X in graph G2 described above.

[0064] Returning to Figure 2, the explanation continues. Once the detection phase processing is complete, the charging state control unit 174 executes the second setting phase processing. The second setting phase processing is executed by the charging state control unit 174 when the foreign object detection unit 173 detects that there is a foreign object between the power transmission coil 12 and the power receiving coil 22.

[0065] Specifically, the second setting phase involves the charging state control unit 174 sending a configuration information request to the terminal device 20 and receiving configuration information from the terminal device 20 as a response to the configuration information request. Once the charging state control unit 174 receives the configuration information from the terminal device 20, it completes the second setting phase.

[0066] Furthermore, once the charging state control unit 174 completes the processing of the first setting phase, it executes the processing of the first negotiation phase. Specifically, the processing of the first negotiation phase involves the charging state control unit 174 transmitting power contract information, including the first power level that can be transmitted, to the terminal device 20, and then receiving a power contract request from the terminal device 20, which includes a first power level calculated by taking into account the first power level that can be transmitted and the power level that can be received.

[0067] The charging state control unit 174 determines that there are no foreign objects between the transmitting coil 12 and the receiving coil 22, and sets a level corresponding to high power as the first power level at which power can be transmitted. Based on this, the charging state control unit 174 negotiates a power contract with the terminal device 20. Upon receiving a power contract request from the terminal device 20, the charging state control unit 174 terminates the processing of the first negotiation phase.

[0068] Furthermore, once the second setting phase processing is complete, the charging state control unit 174 executes the second negotiation phase processing. Specifically, the second negotiation phase processing involves the charging state control unit 174 transmitting power contract information, including the second power level that can be transmitted, to the terminal device 20, and then receiving a power contract request from the terminal device 20, which includes a second power level calculated by taking into account the second power level that can be transmitted and the power level that can be received.

[0069] The charging state control unit 174 determines that there is foreign matter between the transmitting coil 12 and the receiving coil 22, and sets a low power level as the second power level at which power can be transmitted. Based on this, the charging state control unit 174 negotiates a power contract with the terminal device 20. Upon receiving the power contract request from the terminal device 20, the charging state control unit 174 terminates the processing of the second negotiation phase.

[0070] Then, once the charging state control unit 174 has completed processing in the first negotiation phase, it executes processing in the first power transfer phase. Specifically, in the first power transfer phase, the charging state control unit 174 transmits power from the terminal device 20 in accordance with the power contract request, which includes a first power level, received from the terminal device 20.

[0071] Once the processing of the second negotiation phase is complete, the charging state control unit 174 executes the processing of the second power transmission phase. Specifically, the processing of the second power transmission phase involves the charging state control unit 174 transmitting power from the terminal device 20 in accordance with the power contract request, which includes the second power level, received from the terminal device 20.

[0072] If the charging state control unit 174 does not detect any foreign matter between the transmitting coil 12 and the receiving coil 22 before the transmitting coil 12 transmits power to the receiving coil 22, it adds a first correction term to the calculation formula used for detecting foreign matter during wireless charging, according to a first distance indicating the height distance between the transmitting coil 12 and the receiving coil 22. For example, once the processing of the first power transmission phase is complete, the charging state control unit 174 adds a first correction term to the calculation formula used for detecting foreign matter during wireless charging in the MPLA (MPP (Magnetic Power Profile) Power Loss Accounting) method defined in the Qi standard.

[0073] Here, the formula for calculating foreign object detection during wireless charging in the MPLA method as defined in the Qi standard is P ＦO (Power loss due to foreign matter) = P ＰＴ (Transmission power) -PＰＲ (received power). In addition, the first correction term is P ｄｉｓｔ　ｌｏｓｓ . Specifically, the charging state control unit 174 adds the first correction term to the calculation formula described above, and the calculation formula after addition is P ＦO = P ＰＴ - P ＰＲ - P ｄｉｓｔ　ｌｏｓｓ . P ｄｉｓｔ　ｌｏｓｓ is a constant parameter α, transmitted power P ＰＴ and the distance d [mm] in the height direction between the power transmission coil 12 and the power receiving coil 22, then P ｄｉｓｔ　ｌｏｓｓ＝ α*P ＰＴ *d ２ . The constant parameter α is determined according to a pre-measured result.

[0074] Thereby, the charging state control unit 174 can calculate the power loss caused by a foreign object corresponding to the height direction between the power transmission coil 12 and the power receiving coil 22. Therefore, the charging device 10 can improve the accuracy of foreign object detection between the charging device 10 and the terminal device 20 corresponding to the positional relationship between the power transmission coil 12 and the power receiving coil 22 in wireless charging.

[0075] The charging state control unit 174 performs charging start control for starting wireless charging for the terminal device 20. Specifically, after the processing of the first power transmission phase is completed, and the first correction term is added to the calculation formula for foreign object detection during wireless charging, the charging state control unit 174 performs charging start control for starting wireless charging for the terminal device 20. In addition, after executing the processing of the second power transmission phase, the charging state control unit 174 performs charging start control for starting wireless charging for the terminal device 20.

[0076] Furthermore, the foreign object detection unit 173 acquires the transmitted power supplied by the charging device 10 and the received power received by the terminal device 20, which are supplied from the current detection circuit 106. The received power received by the terminal device 20 is periodically notified from the terminal device 20 to the controller 17.

[0077] Then, in the case of processing in the first setting phase, the foreign object detection unit 173 performs a detection process to detect foreign objects present between the power transmission coil 12 and the power reception coil 22 after wireless charging has started, based on the acquired power transmission power, power reception power and first correction term, and a calculation formula used for foreign object detection. Specifically, the foreign object detection unit 173 calculates the foreign object detection formula for wireless charging in the processing of the first setting phase: P ＦO = P ＰＴ -P ＰＲ -P ｄｉｓｔ　ｌｏｓｓ The acquired values ​​of power transmission and power reception are substituted into the respective values, and a foreign object detection process is performed to detect foreign objects present between the power transmission coil 12 and the power reception coil 22 after wireless charging has started.

[0078] Furthermore, in the case of processing in the second setting phase, the foreign object detection unit 173 performs a detection process to detect foreign objects present between the power transmission coil 12 and the power reception coil 22 after wireless charging has started, based on the acquired power transmission and power reception values, and based on a calculation formula used for foreign object detection. Specifically, the foreign object detection unit 173 uses the following calculation formula for foreign object detection during wireless charging in the processing of the second setting phase: P ＦO = P ＰＴ -P ＰＲ The acquired values ​​of power transmission and power reception are substituted into the respective values, and a foreign object detection process is performed to detect foreign objects present between the power transmission coil 12 and the power reception coil 22 after wireless charging has started.

[0079] Figure 4 is a flowchart showing an example of the processing flow performed by the charging device 10 according to this embodiment.

[0080] When the terminal device 20 is placed on the mounting surface 11, the terminal position detection control unit 171 detects the position of the terminal device 20 (step S41). Next, the position detection circuit 110 detects the position of the power receiving coil 22 (step S42). Subsequently, the power transmission coil control unit 172 sets the position of the power transmission coil 12 to a position opposite the power receiving coil 22 based on the position of the power receiving coil 22 detected by the position detection circuit 110, and controls the movement mechanism 15 to move. Then, the power transmission coil 12 is moved by the movement mechanism 15 to the position set by the power transmission coil control unit 172 (step S43).

[0081] Next, the foreign object detection unit 173 performs a foreign object detection process (step S44). Subsequently, the foreign object detection unit 173 determines whether there is any foreign object between the power transmission coil 12 and the power receiving coil 22 before the power transmission coil 12 transmits power to the power receiving coil 22 (step S45). If the foreign object detection unit 173 determines that there is no foreign object between the power transmission coil 12 and the power receiving coil 22 (step S45: Yes), the process proceeds to step A. On the other hand, if the foreign object detection unit 173 determines that there is a foreign object between the power transmission coil 12 and the power receiving coil 22 (step S45: No), the process proceeds to step S46.

[0082] Figure 5 is a flowchart illustrating an example of the processing flow performed by the charging device 10 according to this embodiment. Figure 5 explains the content of the processing that follows from processing A shown in Figure 4.

[0083] The charging state control unit 174 performs the detection phase processing (step S51). Subsequently, the charging state control unit 174 performs the first setting phase processing (step S52). Subsequently, the charging state control unit 174 performs the first negotiation phase processing (step S53).

[0084] Next, the charging state control unit 174 executes the processing of the first power transmission phase (step S54). Subsequently, the charging state control unit 174 adds a first correction term to the calculation formula used for detecting foreign objects during wireless charging (step S55). Subsequently, the charging state control unit 174 performs charging start control on the terminal device 20 to start wireless charging (step S56). When the processing in step S56 is completed, the charging device 10 terminates this process.

[0085] Figure 6 is a flowchart illustrating an example of the processing flow performed by the charging device 10 according to this embodiment. Figure 6 describes the processing content that follows from processing B shown in Figure 4. Furthermore, steps S51, S52, and S56 shown in Figure 6 have the same processing content as steps S51, S52, and S56 shown in Figure 5, so their explanation is omitted.

[0086] In step S61, the charge state control unit 174 performs the processing of the second setting phase (step S61). Subsequently, the charge state control unit 174 performs the processing of the second negotiation phase (step S62). Subsequently, the charge state control unit 174 performs the processing of the second power transmission phase (step S63).

[0087] As described above, a charging device 10 according to one aspect of the present disclosure is a charging device 10 that performs wireless charging on a terminal device 20 having a receiving coil 22 that is arranged on a mounting surface 11 and receives power transmitted wirelessly. The charging device 10 comprises a power transmission coil 12 that transmits power to the terminal device 20 and a controller 17. Before starting wireless charging, if the controller 17 does not detect any foreign matter present between the power transmission coil 12 and the power receiving coil 22, it adds a first correction term to the calculation formula used for detecting foreign matter during wireless charging, according to a first distance indicating the height distance between the power transmission coil 12 and the power receiving coil 22, to correct for power loss due to foreign matter after power transmission from the power transmission coil 12 to the power receiving coil 22. Furthermore, after starting wireless charging, the controller 17 performs a detection process to detect any foreign matter present between the power transmission coil 12 and the power receiving coil 22 based on the calculation formula.

[0088] Furthermore, the controller 17 according to this disclosure calculates a first distance based on a coupling coefficient that indicates the degree of inductive coupling between the transmitting coil 12 and the receiving coil 22. In addition, if the second distance, which indicates the distance between the transmitting coil 12 and the receiving coil 22 in the X and Y directions, is approximately equal, the controller 17 adds a first correction term to the calculation formula.

[0089] As a result, if the charging device 10 does not detect any foreign matter between the transmitting coil 12 and the receiving coil 22 before the transmitting coil 12 transmits power to the receiving coil 22, it calculates the power loss due to the foreign matter corresponding to the height difference between the transmitting coil 12 and the receiving coil 22. The charging device 10 then adds a first correction term to the calculation formula used for detecting foreign matter during wireless charging, which corrects for the power loss due to foreign matter after the transmitting coil 12 has transmitted power to the receiving coil 22. Therefore, the charging device 10 can improve the accuracy of detecting foreign matter between the charging device 10 and the terminal device 20, corresponding to the positional relationship between the transmitting coil 12 and the receiving coil 22 during wireless charging.

[0090] Although the distance is calculated from the coupling coefficient, it may also be detected using a distance-measuring sensor or the like. Furthermore, the distance may be obtained by storing or inputting design values ​​such as the thickness of the cover or case installed on the smartphone or the thickness of the smartphone's casing into the charging device 10.

[0091] The embodiments described above can also be modified and implemented as appropriate by changing some of the configurations or functions of each of the devices described above. Therefore, several modifications of the embodiments described above will be described below as other embodiments. In the following, we will mainly describe the differences from the embodiments described above, and will omit detailed explanations of points that are common with what has already been described.

[0092] (First Modification) For example, the user may place the terminal device 20 on the mounting surface 11 outside the movable range of the power transmission coil 12. In the first modification, the content of the process that the charging device 10 operates on the terminal device 20 placed on the mounting surface 11 outside the movable range of the power transmission coil 12 will be described.

[0093] The power transmission coil control unit 172 controls the movement of the moving mechanism 15 to set the power transmission coil 12 to a position facing the nearest power transmission coil 22 within its movable range, based on the position of the power receiving coil 22 detected by the position detection circuit 110. Specifically, the power transmission coil control unit 172 uses the moving mechanism 15 to move the power transmission coil 12 to the position of the nearest power receiving coil 22 within its movable range, according to the position of the power receiving coil 22 detected by the position detection circuit 110. Then, the power transmission coil 12 is moved by the moving mechanism 15 to the position of the nearest power receiving coil 22 within its movable range, as set by the power transmission coil control unit 172, and various authentications are performed between the charging device 10 and the terminal device 20.

[0094] The charging state control unit 174 calculates the distance in the X and Y directions between the position of the transmitting coil 12 and the position of the receiving coil 22. Specifically, the charging state control unit 174 calculates the distance in the X and Y directions between the position of the transmitting coil 12 and the position of the receiving coil 22 by taking the difference between the position of the boundary coordinate of the movable range to which the transmitting coil 12 has moved, as set by the transmitting coil control unit 172, and the position of the receiving coil 22 detected by the position detection circuit 110.

[0095] Next, we will explain the process performed by the charging state control unit 174 when there is no foreign matter between the power transmission coil 12 of the charging device 10 and the power receiving coil 22 of the terminal device 20 which is placed on the mounting surface 11 outside the movable range of the power transmission coil 12.

[0096] The charging state control unit 174 executes the processing of the third setting phase once the processing of the detection phase is completed. The processing of the third setting phase is executed by the charging state control unit 174 when the foreign object detection unit 173 detects that there is no foreign object between the power transmission coil 12 and the power receiving coil 22.

[0097] Specifically, the processing in the third setting phase involves the charging state control unit 174 sending a configuration information request to the terminal device 20 and receiving configuration information from the terminal device 20 as a response to the configuration information request. The charging state control unit 174 also calculates the coupling coefficient k using the voltage included in the configuration information. The configuration information here, as described above, is information exchanged between the charging device 10 and the terminal device 20, and includes information measured or calculated by the charging device 10, or individual information of the terminal device 20.

[0098] Furthermore, the charging state control unit 174 calculates the height distance between the transmitting coil 12 and the receiving coil 22 based on the calculated coupling coefficient k and the distance in the X and Y directions between the position of the transmitting coil 12 and the position of the receiving coil 22. Here, in the processing of the third setting phase, the height distance between the transmitting coil 12 and the receiving coil 22 is also referred to as the third distance. Next, the height distance between the transmitting coil 12 and the receiving coil 22 calculated by the charging state control unit 174 will be explained using Figure 7.

[0099] Figure 7 is a schematic diagram illustrating the height distance between the transmitting coil 12 and the receiving coil 22 in the first modified example. Figure 7 is a graph showing the relationship between the X-axis displacement between the positions of the transmitting coil 12 and the receiving coil 22 and the coupling coefficient. The graph shown in Figure 7 is a two-axis graph with the horizontal axis representing the displacement [mm] and the vertical axis representing the coupling coefficient.

[0100] Graphs G71, G72, G73, G74, G75, G76, and G77 shown in Figure 7 are data obtained by measuring the coupling coefficient when the charging device 10 is shifted in the X-axis direction with respect to each height direction relative to the terminal device 20 placed on the mounting surface 11. Graph G71 corresponds to a height distance of 2 [mm]. Graph G72 corresponds to a height distance of 3 [mm]. Graph G73 corresponds to a height distance of 4 [mm]. Graph G74 corresponds to a height distance of 5 [mm]. Graph G75 corresponds to a height distance of 6 [mm]. Graph G76 corresponds to a height distance of 7.5 [mm]. Graph G77 corresponds to a height distance of 9 [mm].

[0101] Here, the power loss correction term for distance in the XY direction is assumed to be the same as the power loss correction term for the height distance between the transmitting coil 12 and the receiving coil 22. This is because, if r is the Euclidean distance in the XY plane and z is the height distance, in the MPLA system, for example, the power losses for (r, z) = (0, 3) and (3, 0), and (3, 2) and (2, 3) are approximately equal. In other words, the distance in the calculation formula for foreign object detection during wireless charging can also be replaced with the Euclidean distance.

[0102] In other words, the charging state control unit 174 calculates the Euclidean distance between the transmitting coil 12 and the receiving coil 22 based on the second and third distances. For example, if the coupling coefficient is 0.4 and the distance in the XY direction is 5 [mm], point P1 is defined as the point where the horizontal axis and vertical axis intersect. The charging state control unit 174 identifies graph G76, which intersects point P1, from the graphs shown in Figure 7. As described above, since the height of graph G76 is 7.5 [mm], the charging state control unit 174 can calculate that the height distance between the transmitting coil 12 and the receiving coil 22 is 7.5 [mm]. Alternatively, the transition graph of the coupling coefficient in Figure 7 may be converted into a table and stored in ROM to perform processing equivalent to the calculation.

[0103] If the charging state control unit 174 is located outside the movable range of the transmitting coil 12, and the second distance, which indicates the distance between the transmitting coil 12 and the receiving coil 22 in the X and Y directions, is different, and no foreign object is detected between the transmitting coil 12 and the receiving coil 22, then the charging state control unit 174 adds a second correction term to the calculation formula used for detecting foreign objects during wireless charging, according to the second and third distances, to correct for power loss. For example, once the processing of the first power transmission phase is complete, the charging state control unit 174 adds a second correction term to the calculation formula for detecting foreign objects during wireless charging in the MPLA method as defined in the Qi standard. The second correction term is P ｄｉｓｔ　ｌｏｓｓ P ｄｉｓｔ　ｌｏｓｓ＝ A*P ＰＴ *d ２ Here, the distance d [mm] is the Euclidean distance corresponding to the height distance between the transmitting coil 12 and the receiving coil 22, which was calculated in the processing of the third setting phase.

[0104] Then, in the case of processing in the third setting phase, the foreign object detection unit 173 determines a calculation formula to be used for detecting foreign objects during wireless charging after the start of wireless charging, based on the acquired transmitted power, received power and second correction term, and performs a detection process to detect foreign objects present between the transmitted coil 12 and the received coil 22. Specifically, the foreign object detection unit 173 calculates the foreign object detection formula for detecting foreign objects during wireless charging in the processing of the third setting phase: P ＦO = P ＰＴ -P ＰＲ -P ｄｉｓｔ　ｌｏｓｓ The acquired values ​​of power transmission and power reception are substituted into the respective values, and after wireless charging starts, a detection process is performed to detect foreign objects present between the power transmission coil 12 and the power reception coil 22 based on the calculation formula.

[0105] As a result, the charging state control unit 174 can calculate the power loss due to foreign objects corresponding to the XY direction and height direction of the transmitting coil 12 and the receiving coil 22. Therefore, the charging device 10 can improve the accuracy of foreign object detection between the charging device 10 and the terminal device 20, which corresponds to the positional relationship between the transmitting coil 12 and the receiving coil 22 in wireless charging.

[0106] Next, we will explain the process that the charging state control unit 174 performs when there is foreign matter between the power transmission coil 12 of the charging device 10 and the power receiving coil 22 of the terminal device 20 which is placed on the mounting surface 11 outside the movable range of the power transmission coil 12.

[0107] The charging state control unit 174, upon detecting foreign matter between the transmitting coil 12 and the receiving coil 22, adds a third correction term to compensate for power loss according to the second distance. Specifically, after completing the processing of the second power transmission phase, the charging state control unit 174 adds a third correction term to the calculation formula for foreign matter detection during wireless charging in the MPLA method as defined in the Qi standard. Here, the third correction term is a value of power loss corresponding to the distance in the X and Y directions between the position of the transmitting coil 12 and the position of the receiving coil 22. This value of power loss is, for example, one defined in the Qi standard or a value calculated by the charging device 10 through prior simulation.

[0108] Furthermore, in the case of processing in the fourth setting phase, the foreign object detection unit 173 determines a calculation formula to be used for detecting foreign objects during wireless charging after the start of wireless charging, based on the acquired transmitted power, received power and third correction term, and performs a detection process to detect foreign objects present between the transmitting coil 12 and the receiving coil 22. Specifically, the foreign object detection unit 173 calculates the foreign object detection formula for detecting foreign objects during wireless charging in the processing of the fourth setting phase: P ＦO = P ＰＴ -P ＰＲ -P ｄｉｓｔ　ｌｏｓｓ The acquired values ​​of power transmission and power reception are substituted into the respective values, and after wireless charging starts, a detection process is performed to detect foreign objects present between the power transmission coil 12 and the power reception coil 22 based on the calculation formula.

[0109] As a result, the charging state control unit 174 can define the power loss due to foreign matter corresponding to the distance in the X and Y directions between the positions of the transmitting coil 12 and the receiving coil 22. Therefore, the charging device 10 can improve the accuracy of foreign matter detection between the charging device 10 and the terminal device 20, which corresponds to the positional relationship between the transmitting coil 12 and the receiving coil 22 in wireless charging.

[0110] Figure 8 is a flowchart showing an example of the processing flow performed by the charging device 10 according to the first modified example. Steps S41, S42, S44, and S45 shown in Figure 8 are the same processing as steps S41, S42, S44, and S45 shown in Figure 4, so their explanation is omitted.

[0111] In step S81, the power transmission coil control unit 172 sets the position of the power transmission coil 12 to a position facing the nearest power receiving coil 22 within the movable range, based on the position of the power receiving coil 22 detected by the position detection circuit 110, and controls the movement mechanism 15 to move. The power transmission coil 12 is then moved by the movement mechanism 15 to the position of the nearest power receiving coil 22 within the movable range, as set by the power transmission coil control unit 172 (step S81).

[0112] In step S82, the charging state control unit 174 calculates the distance in the XY direction between the position of the power transmission coil 12 and the position of the power receiving coil 22 (step S82).

[0113] Figure 9 is a flowchart showing an example of the processing flow performed by the charging device 10 according to the first modified example. Figure 9 explains the content of the processing that follows from processing C shown in Figure 8. Furthermore, steps S51, S53, S54, and S56 shown in Figure 9 have the same processing content as steps S51, S53, S54, and S56 shown in Figure 5, so their explanation is omitted.

[0114] In step S91, the charging state control unit 174 performs the processing of the third setting phase (step S91). In step S92, the charging state control unit 174 adds a second correction term to the calculation formula for foreign object detection during wireless charging (step S92).

[0115] Figure 10 is a flowchart showing an example of the processing flow performed by the charging device 10 according to the first modified example. Figure 10 explains the content of the processing that follows from processing D shown in Figure 8. Steps S51 and S56 shown in Figure 10 have the same processing content as steps S51 and S56 shown in Figure 5, so their explanation is omitted. Furthermore, steps S61, S62 and S63 shown in Figure 10 have the same processing content as steps S61, S62 and S63 shown in Figure 6, so their explanation is omitted.

[0116] In step S93, the charging state control unit 174 adds a third correction term to the calculation formula for detecting foreign objects during wireless charging (step S93).

[0117] As described above, in the first modified charging device 10, if the terminal device 20 is outside the movable range of the transmitting coil 12, the second distance is different, and foreign matter present between the transmitting coil 12 and the receiving coil 22 is not detected, the controller 17 adds a second correction term to the calculation formula to correct power loss according to the second distance and the third distance, which indicates the height distance between the transmitting coil 12 and the receiving coil 22. Furthermore, after wireless charging starts, the controller 17 performs a detection process to detect foreign matter present between the transmitting coil 12 and the receiving coil 22 based on the calculation formula.

[0118] For example, if the user places the terminal device 20 on the mounting surface 11 outside the movable range of the power transmission coil 12, and does not detect any foreign matter between the power transmission coil 12 and the power receiving coil 22, the charging device 10 calculates the power loss due to the foreign matter corresponding to the XY direction and height direction of the power transmission coil 12 and the power receiving coil 22. The charging device 10 then adds a second correction term to the calculation formula used for detecting foreign matter during wireless charging, which corrects for the power loss due to foreign matter after power transmission from the power transmission coil 12 to the power receiving coil 22. Therefore, the charging device 10 can improve the accuracy of detecting foreign matter between the charging device 10 and the terminal device 20, which corresponds to the positional relationship between the power transmission coil 12 and the power receiving coil 22 during wireless charging.

[0119] Furthermore, the controller 17 calculates a third distance based on the second distance and the coupling coefficient, which indicates the degree of inductive coupling between the transmitting coil 12 and the receiving coil 22. In addition, the controller 17 calculates the Euclidean distance between the transmitting coil 12 and the receiving coil 22 based on the second and third distances, and the second correction term corresponds to the Euclidean distance. When the controller 17 detects foreign matter present between the transmitting coil 12 and the receiving coil 22, it adds a third correction term to the calculation formula to correct power loss according to the second distance. Furthermore, after wireless charging starts, the controller 17 performs a detection process to detect foreign matter present between the transmitting coil 12 and the receiving coil 22 based on the calculation formula.

[0120] For example, if a user places the terminal device 20 on the mounting surface 11 outside the movable range of the power transmission coil 12 and detects foreign matter present between the power transmission coil 12 and the power receiving coil 22, the charging device 10 calculates the power loss due to the foreign matter corresponding to the XY direction and height direction of the power transmission coil 12 and the power receiving coil 22. The charging device 10 then adds a third correction term to the calculation formula to compensate for the power loss due to the foreign matter after power transmission from the power transmission coil 12 to the power receiving coil 22. Therefore, the charging device 10 can improve the accuracy of foreign matter detection between the charging device 10 and the terminal device 20, which corresponds to the positional relationship between the power transmission coil 12 and the power receiving coil 22 in wireless charging.

[0121] Furthermore, the processing of the transmission coil 12 within and outside its movable range may be separated, and since the XY distance is approximately zero within the movable range, the addition of a correction term within the movable range may be omitted. In addition, since the relationship between the coupling coefficient and distance differs depending on the terminal device 20, the description assumes that it is calculated or estimated before or during wireless charging, but the relationship between the coupling coefficient and distance may be obtained by maintaining a characteristic table corresponding to the terminal device 20 or by inputting it from an external source. In that case, the charging device 10 may acquire the solid-state information of the terminal device 20 as configuration information and optimize it.

[0122] (Hardware Configuration) Figure 11 shows an example of the hardware configuration of the charging system 100 according to the embodiment and modified example. The charging device 10 and terminal device 20 of the charging system 100 according to the embodiment and modified example are interconnected by a bus 45, etc., and the processor 41, main memory 42, auxiliary storage 43, and device I / F 44 are connected to each other. This results in a hardware configuration that utilizes a normal computer.

[0123] The processor 41 is, for example, a CPU (Central Processing Unit) and is an arithmetic unit that controls the charging device 10 and terminal device 20 of the above embodiment and its modified form. The main memory 42 is, for example, a RAM (Random Access Memory) and stores data necessary for various processes performed by the processor 41. The auxiliary memory 43 is, for example, a ROM (Read Only Memory) and stores programs and the like that realize information processing by the processor 41.

[0124] The device interface 44 is an interface for various inputs / outputs and / or communications of the charging device 10 and the terminal device 20. For example, the device interface 44 may include a communication interface configured to allow connection of an external communication device that communicates with the charging device 10 and the terminal device 20, or configured to function as such a communication device.

[0125] As a communication interface, wired communication circuits such as USB (Universal Serial Bus®) and Ethernet®, or wireless communication circuits compatible with various standards such as 3G, LTE, 4G, 5G, 6G, Wi-Fi®, and Bluetooth® can be used as appropriate.

[0126] In the above embodiment and modified versions of the charging device 10 and terminal device 20, the processor 41 reads a program from the auxiliary storage device 43 onto the main memory device 42 and executes it, thereby realizing each of the above-mentioned functional units on the computer.

[0127] Furthermore, the programs for executing the above-mentioned processes performed by the charging device 10 and terminal device 20 of the above embodiment and modified version may be stored in an HDD (hard disk drive). Alternatively, the programs for executing the above-mentioned processes performed by the charging device 10 and terminal device 20 of the above embodiment and modified version may be pre-installed and provided in an auxiliary storage device 43.

[0128] Furthermore, the program for executing the above-mentioned processing performed by the charging device 10 and terminal device 20 of the above-described embodiment and modified version may be provided as a computer program product by being stored in an installable or executable file format on a computer-readable storage medium such as a CD-ROM, CD-R, memory card, DVD (Digital Versatile Disk), or flexible disk (FD). Alternatively, the program for executing the above-mentioned information processing performed by the charging device 10 and terminal device 20 of the above-described embodiment and modified version may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Alternatively, the program for executing the above-mentioned information processing performed by the charging device 10 and terminal device 20 of the above-described embodiment and modified version may be provided or distributed via a network such as the Internet.

[0129] According to at least one embodiment described above, the accuracy of foreign object detection between the charging device 10 and the terminal device 20, corresponding to the positional relationship between the transmitting coil 12 and the receiving coil 22 in wireless charging, can be improved.

[0130] While several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0131] 10 Charging device 11 Mounting surface 12 Power transmission coil 15 Moving mechanism 16 Detection coil 17 Controller 20 Terminal device 22 Power receiving coil 100 Charging system 101 DC power supply 102 DC-DC converter circuit 103 Inverter circuit 105 Voltage detection circuit 106 Current detection circuit 108 Terminal signal demodulation circuit 109 Position detection pattern coil 110 Position detection circuit 171 Terminal position detection control unit 172 Power transmission coil control unit 173 Foreign object detection unit 174 Charging state control unit

Claims

1. A charging device for wirelessly charging a terminal device having a receiving coil that receives power wirelessly transmitted power and is placed on a mounting surface, comprising: a transmitting coil that transmits power to the terminal device; and a controller, wherein, before wireless charging starts, if the controller does not detect any foreign matter between the transmitting coil and the receiving coil, it adds a first correction term to a calculation formula used for detecting foreign matter during wireless charging, which corrects for power loss due to the foreign matter after the power has been transmitted from the transmitting coil to the receiving coil, according to a first distance indicating the height distance between the transmitting coil and the receiving coil, and after wireless charging starts, it performs a detection process to detect any foreign matter between the transmitting coil and the receiving coil based on the calculation formula.

2. The charging device according to claim 1, wherein the controller calculates the first distance based on a coupling coefficient indicating the degree of inductive coupling between the power transmission coil and the power reception coil.

3. The charging device according to claim 1, wherein the controller adds the first correction term to the calculation formula when the second distance, which indicates the horizontal distance between the power transmitting coil and the power receiving coil, is substantially equal.

4. The charging device according to claim 3, wherein, if the terminal device is located outside the movable range of the power transmission coil, the second distance is different, and no foreign matter is detected between the power transmission coil and the power receiving coil, the controller adds a second correction term to the calculation formula to correct the power loss according to the second distance and a third distance indicating the height distance between the power transmission coil and the power receiving coil, and after the wireless charging starts, the detection process is performed based on the calculation formula.

5. The charging device according to claim 4, wherein the controller calculates the third distance based on the second distance and a coupling coefficient indicating the degree of inductive coupling between the transmitting coil and the receiving coil.

6. The charging device according to claim 5, wherein the controller calculates the Euclidean distance between the transmitting coil and the receiving coil based on the second distance and the third distance, and the second correction term corresponds to the Euclidean distance.

7. The charging device according to claim 6, wherein the controller, when it detects foreign matter present between the power transmitting coil and the power receiving coil, adds a third correction term to the calculation formula to correct the power loss according to the second distance, and after the wireless charging starts, performs the detection process based on the calculation formula.

8. A control method for wirelessly charging a terminal device having a receiving coil that is placed on a mounting surface and receives wirelessly transmitted power, and for the charging method to be performed by a charging device having a transmitting coil that transmits power to the terminal device, wherein, if no foreign matter is detected between the transmitting coil and the receiving coil before wireless charging starts, a first correction term is added to a calculation formula used for detecting foreign matter during wireless charging, which corrects for power loss due to the foreign matter after the power has been transmitted from the transmitting coil to the receiving coil, according to a first distance indicating the height distance between the transmitting coil and the receiving coil, and after wireless charging starts, a detection process is performed to detect foreign matter present between the transmitting coil and the receiving coil based on the calculation formula.

Images